trace.c 89.8 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
/*
 * ring buffer based function tracer
 *
 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
 *
 * Originally taken from the RT patch by:
 *    Arnaldo Carvalho de Melo <acme@redhat.com>
 *
 * Based on code from the latency_tracer, that is:
 *  Copyright (C) 2004-2006 Ingo Molnar
 *  Copyright (C) 2004 William Lee Irwin III
 */
14
#include <linux/ring_buffer.h>
15
#include <linux/utsrelease.h>
16
17
#include <linux/stacktrace.h>
#include <linux/writeback.h>
18
19
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
20
#include <linux/notifier.h>
21
#include <linux/irqflags.h>
22
#include <linux/debugfs.h>
23
#include <linux/pagemap.h>
24
25
26
#include <linux/hardirq.h>
#include <linux/linkage.h>
#include <linux/uaccess.h>
27
#include <linux/kprobes.h>
28
29
30
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/percpu.h>
31
#include <linux/splice.h>
32
#include <linux/kdebug.h>
33
34
#include <linux/ctype.h>
#include <linux/init.h>
35
#include <linux/poll.h>
36
37
#include <linux/gfp.h>
#include <linux/fs.h>
Ingo Molnar's avatar
Ingo Molnar committed
38

39
#include "trace.h"
40
#include "trace_output.h"
41

42
43
#define TRACE_BUFFER_FLAGS	(RB_FL_OVERWRITE)

44
unsigned long __read_mostly	tracing_max_latency;
45
46
unsigned long __read_mostly	tracing_thresh;

47
48
/*
 * We need to change this state when a selftest is running.
49
50
51
52
53
 * A selftest will lurk into the ring-buffer to count the
 * entries inserted during the selftest although some concurrent
 * insertions into the ring-buffer such as ftrace_printk could occurred
 * at the same time, giving false positive or negative results.
 */
54
static bool __read_mostly tracing_selftest_running;
55

56
57
58
59
60
/*
 * If a tracer is running, we do not want to run SELFTEST.
 */
static bool __read_mostly tracing_selftest_disabled;

61
62
63
64
65
66
67
68
69
70
71
72
73
74
/* For tracers that don't implement custom flags */
static struct tracer_opt dummy_tracer_opt[] = {
	{ }
};

static struct tracer_flags dummy_tracer_flags = {
	.val = 0,
	.opts = dummy_tracer_opt
};

static int dummy_set_flag(u32 old_flags, u32 bit, int set)
{
	return 0;
}
75
76
77
78
79
80
81

/*
 * Kill all tracing for good (never come back).
 * It is initialized to 1 but will turn to zero if the initialization
 * of the tracer is successful. But that is the only place that sets
 * this back to zero.
 */
82
static int tracing_disabled = 1;
83

84
85
86
87
88
89
90
91
92
93
94
95
96
97
static DEFINE_PER_CPU(local_t, ftrace_cpu_disabled);

static inline void ftrace_disable_cpu(void)
{
	preempt_disable();
	local_inc(&__get_cpu_var(ftrace_cpu_disabled));
}

static inline void ftrace_enable_cpu(void)
{
	local_dec(&__get_cpu_var(ftrace_cpu_disabled));
	preempt_enable();
}

98
static cpumask_var_t __read_mostly	tracing_buffer_mask;
99

100
101
102
/* Define which cpu buffers are currently read in trace_pipe */
static cpumask_var_t			tracing_reader_cpumask;

103
#define for_each_tracing_cpu(cpu)	\
104
	for_each_cpu(cpu, tracing_buffer_mask)
105

106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
/*
 * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
 *
 * If there is an oops (or kernel panic) and the ftrace_dump_on_oops
 * is set, then ftrace_dump is called. This will output the contents
 * of the ftrace buffers to the console.  This is very useful for
 * capturing traces that lead to crashes and outputing it to a
 * serial console.
 *
 * It is default off, but you can enable it with either specifying
 * "ftrace_dump_on_oops" in the kernel command line, or setting
 * /proc/sys/kernel/ftrace_dump_on_oops to true.
 */
int ftrace_dump_on_oops;

121
122
123
124
125
static int tracing_set_tracer(const char *buf);

#define BOOTUP_TRACER_SIZE		100
static char bootup_tracer_buf[BOOTUP_TRACER_SIZE] __initdata;
static char *default_bootup_tracer;
126
127
128

static int __init set_ftrace(char *str)
{
129
130
	strncpy(bootup_tracer_buf, str, BOOTUP_TRACER_SIZE);
	default_bootup_tracer = bootup_tracer_buf;
131
132
	return 1;
}
133
__setup("ftrace=", set_ftrace);
134

135
136
137
138
139
140
static int __init set_ftrace_dump_on_oops(char *str)
{
	ftrace_dump_on_oops = 1;
	return 1;
}
__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
Steven Rostedt's avatar
Steven Rostedt committed
141

142
long
143
144
145
146
147
148
149
ns2usecs(cycle_t nsec)
{
	nsec += 500;
	do_div(nsec, 1000);
	return nsec;
}

Ingo Molnar's avatar
Ingo Molnar committed
150
cycle_t ftrace_now(int cpu)
151
{
152
153
154
	u64 ts = ring_buffer_time_stamp(cpu);
	ring_buffer_normalize_time_stamp(cpu, &ts);
	return ts;
155
156
}

Steven Rostedt's avatar
Steven Rostedt committed
157
158
159
160
161
162
163
164
165
166
167
168
/*
 * The global_trace is the descriptor that holds the tracing
 * buffers for the live tracing. For each CPU, it contains
 * a link list of pages that will store trace entries. The
 * page descriptor of the pages in the memory is used to hold
 * the link list by linking the lru item in the page descriptor
 * to each of the pages in the buffer per CPU.
 *
 * For each active CPU there is a data field that holds the
 * pages for the buffer for that CPU. Each CPU has the same number
 * of pages allocated for its buffer.
 */
169
170
171
172
static struct trace_array	global_trace;

static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);

Steven Rostedt's avatar
Steven Rostedt committed
173
174
175
176
177
178
179
180
181
182
/*
 * The max_tr is used to snapshot the global_trace when a maximum
 * latency is reached. Some tracers will use this to store a maximum
 * trace while it continues examining live traces.
 *
 * The buffers for the max_tr are set up the same as the global_trace.
 * When a snapshot is taken, the link list of the max_tr is swapped
 * with the link list of the global_trace and the buffers are reset for
 * the global_trace so the tracing can continue.
 */
183
184
185
186
static struct trace_array	max_tr;

static DEFINE_PER_CPU(struct trace_array_cpu, max_data);

Steven Rostedt's avatar
Steven Rostedt committed
187
/* tracer_enabled is used to toggle activation of a tracer */
188
static int			tracer_enabled = 1;
Steven Rostedt's avatar
Steven Rostedt committed
189

190
191
192
193
194
195
196
197
198
199
200
201
202
/**
 * tracing_is_enabled - return tracer_enabled status
 *
 * This function is used by other tracers to know the status
 * of the tracer_enabled flag.  Tracers may use this function
 * to know if it should enable their features when starting
 * up. See irqsoff tracer for an example (start_irqsoff_tracer).
 */
int tracing_is_enabled(void)
{
	return tracer_enabled;
}

Steven Rostedt's avatar
Steven Rostedt committed
203
/*
204
205
206
 * trace_buf_size is the size in bytes that is allocated
 * for a buffer. Note, the number of bytes is always rounded
 * to page size.
207
208
209
210
211
 *
 * This number is purposely set to a low number of 16384.
 * If the dump on oops happens, it will be much appreciated
 * to not have to wait for all that output. Anyway this can be
 * boot time and run time configurable.
Steven Rostedt's avatar
Steven Rostedt committed
212
 */
213
#define TRACE_BUF_SIZE_DEFAULT	1441792UL /* 16384 * 88 (sizeof(entry)) */
214

215
static unsigned long		trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
216

Steven Rostedt's avatar
Steven Rostedt committed
217
/* trace_types holds a link list of available tracers. */
218
static struct tracer		*trace_types __read_mostly;
Steven Rostedt's avatar
Steven Rostedt committed
219
220

/* current_trace points to the tracer that is currently active */
221
static struct tracer		*current_trace __read_mostly;
Steven Rostedt's avatar
Steven Rostedt committed
222
223
224
225
226
227

/*
 * max_tracer_type_len is used to simplify the allocating of
 * buffers to read userspace tracer names. We keep track of
 * the longest tracer name registered.
 */
228
229
static int			max_tracer_type_len;

Steven Rostedt's avatar
Steven Rostedt committed
230
231
232
233
234
235
/*
 * trace_types_lock is used to protect the trace_types list.
 * This lock is also used to keep user access serialized.
 * Accesses from userspace will grab this lock while userspace
 * activities happen inside the kernel.
 */
236
static DEFINE_MUTEX(trace_types_lock);
Steven Rostedt's avatar
Steven Rostedt committed
237
238

/* trace_wait is a waitqueue for tasks blocked on trace_poll */
239
240
static DECLARE_WAIT_QUEUE_HEAD(trace_wait);

241
/* trace_flags holds trace_options default values */
242
unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
243
	TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO;
244

Steven Rostedt's avatar
Steven Rostedt committed
245
246
247
248
249
250
/**
 * trace_wake_up - wake up tasks waiting for trace input
 *
 * Simply wakes up any task that is blocked on the trace_wait
 * queue. These is used with trace_poll for tasks polling the trace.
 */
251
252
void trace_wake_up(void)
{
Ingo Molnar's avatar
Ingo Molnar committed
253
254
255
256
257
	/*
	 * The runqueue_is_locked() can fail, but this is the best we
	 * have for now:
	 */
	if (!(trace_flags & TRACE_ITER_BLOCK) && !runqueue_is_locked())
258
259
		wake_up(&trace_wait);
}
260

261
static int __init set_buf_size(char *str)
262
{
263
	unsigned long buf_size;
264
265
	int ret;

266
267
	if (!str)
		return 0;
268
	ret = strict_strtoul(str, 0, &buf_size);
269
	/* nr_entries can not be zero */
270
	if (ret < 0 || buf_size == 0)
271
		return 0;
272
	trace_buf_size = buf_size;
273
274
	return 1;
}
275
__setup("trace_buf_size=", set_buf_size);
276

Steven Rostedt's avatar
Steven Rostedt committed
277
278
279
280
281
unsigned long nsecs_to_usecs(unsigned long nsecs)
{
	return nsecs / 1000;
}

Steven Rostedt's avatar
Steven Rostedt committed
282
/* These must match the bit postions in trace_iterator_flags */
283
284
285
286
287
static const char *trace_options[] = {
	"print-parent",
	"sym-offset",
	"sym-addr",
	"verbose",
Ingo Molnar's avatar
Ingo Molnar committed
288
	"raw",
289
	"hex",
Ingo Molnar's avatar
Ingo Molnar committed
290
	"bin",
291
	"block",
Ingo Molnar's avatar
Ingo Molnar committed
292
	"stacktrace",
Ingo Molnar's avatar
Ingo Molnar committed
293
	"sched-tree",
294
	"ftrace_printk",
295
	"ftrace_preempt",
296
	"branch",
297
	"annotate",
298
	"userstacktrace",
299
	"sym-userobj",
300
	"printk-msg-only",
301
	"context-info",
302
303
304
	NULL
};

Steven Rostedt's avatar
Steven Rostedt committed
305
306
307
308
309
310
311
312
313
/*
 * ftrace_max_lock is used to protect the swapping of buffers
 * when taking a max snapshot. The buffers themselves are
 * protected by per_cpu spinlocks. But the action of the swap
 * needs its own lock.
 *
 * This is defined as a raw_spinlock_t in order to help
 * with performance when lockdep debugging is enabled.
 */
314
315
static raw_spinlock_t ftrace_max_lock =
	(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
316
317
318
319
320
321

/*
 * Copy the new maximum trace into the separate maximum-trace
 * structure. (this way the maximum trace is permanently saved,
 * for later retrieval via /debugfs/tracing/latency_trace)
 */
Ingo Molnar's avatar
Ingo Molnar committed
322
static void
323
324
325
326
327
328
329
330
331
332
333
334
__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
	struct trace_array_cpu *data = tr->data[cpu];

	max_tr.cpu = cpu;
	max_tr.time_start = data->preempt_timestamp;

	data = max_tr.data[cpu];
	data->saved_latency = tracing_max_latency;

	memcpy(data->comm, tsk->comm, TASK_COMM_LEN);
	data->pid = tsk->pid;
335
	data->uid = task_uid(tsk);
336
337
338
339
340
	data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
	data->policy = tsk->policy;
	data->rt_priority = tsk->rt_priority;

	/* record this tasks comm */
341
	tracing_record_cmdline(tsk);
342
343
}

344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
{
	int len;
	int ret;

	if (s->len <= s->readpos)
		return -EBUSY;

	len = s->len - s->readpos;
	if (cnt > len)
		cnt = len;
	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
	if (ret)
		return -EFAULT;

	s->readpos += len;
	return cnt;
361
362
}

363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
{
	int len;
	void *ret;

	if (s->len <= s->readpos)
		return -EBUSY;

	len = s->len - s->readpos;
	if (cnt > len)
		cnt = len;
	ret = memcpy(buf, s->buffer + s->readpos, cnt);
	if (!ret)
		return -EFAULT;

	s->readpos += len;
	return cnt;
}

Ingo Molnar's avatar
Ingo Molnar committed
382
static void
383
384
385
386
387
388
389
trace_print_seq(struct seq_file *m, struct trace_seq *s)
{
	int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;

	s->buffer[len] = 0;
	seq_puts(m, s->buffer);

390
	trace_seq_init(s);
391
392
}

Steven Rostedt's avatar
Steven Rostedt committed
393
394
395
396
397
398
399
400
401
/**
 * update_max_tr - snapshot all trace buffers from global_trace to max_tr
 * @tr: tracer
 * @tsk: the task with the latency
 * @cpu: The cpu that initiated the trace.
 *
 * Flip the buffers between the @tr and the max_tr and record information
 * about which task was the cause of this latency.
 */
Ingo Molnar's avatar
Ingo Molnar committed
402
void
403
404
update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
405
	struct ring_buffer *buf = tr->buffer;
406

407
	WARN_ON_ONCE(!irqs_disabled());
408
	__raw_spin_lock(&ftrace_max_lock);
409
410
411
412

	tr->buffer = max_tr.buffer;
	max_tr.buffer = buf;

413
	ftrace_disable_cpu();
414
	ring_buffer_reset(tr->buffer);
415
	ftrace_enable_cpu();
416
417

	__update_max_tr(tr, tsk, cpu);
418
	__raw_spin_unlock(&ftrace_max_lock);
419
420
421
422
423
424
425
}

/**
 * update_max_tr_single - only copy one trace over, and reset the rest
 * @tr - tracer
 * @tsk - task with the latency
 * @cpu - the cpu of the buffer to copy.
Steven Rostedt's avatar
Steven Rostedt committed
426
427
 *
 * Flip the trace of a single CPU buffer between the @tr and the max_tr.
428
 */
Ingo Molnar's avatar
Ingo Molnar committed
429
void
430
431
update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
432
	int ret;
433

434
	WARN_ON_ONCE(!irqs_disabled());
435
	__raw_spin_lock(&ftrace_max_lock);
436

437
438
	ftrace_disable_cpu();

439
440
441
	ring_buffer_reset(max_tr.buffer);
	ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);

442
443
	ftrace_enable_cpu();

444
	WARN_ON_ONCE(ret && ret != -EAGAIN);
445
446

	__update_max_tr(tr, tsk, cpu);
447
	__raw_spin_unlock(&ftrace_max_lock);
448
449
}

Steven Rostedt's avatar
Steven Rostedt committed
450
451
452
453
454
455
/**
 * register_tracer - register a tracer with the ftrace system.
 * @type - the plugin for the tracer
 *
 * Register a new plugin tracer.
 */
456
int register_tracer(struct tracer *type)
457
458
__releases(kernel_lock)
__acquires(kernel_lock)
459
460
461
462
463
464
465
466
467
468
{
	struct tracer *t;
	int len;
	int ret = 0;

	if (!type->name) {
		pr_info("Tracer must have a name\n");
		return -1;
	}

Ingo Molnar's avatar
Ingo Molnar committed
469
470
471
472
473
474
475
	/*
	 * When this gets called we hold the BKL which means that
	 * preemption is disabled. Various trace selftests however
	 * need to disable and enable preemption for successful tests.
	 * So we drop the BKL here and grab it after the tests again.
	 */
	unlock_kernel();
476
	mutex_lock(&trace_types_lock);
Ingo Molnar's avatar
Ingo Molnar committed
477

478
479
	tracing_selftest_running = true;

480
481
482
483
484
485
486
487
488
489
	for (t = trace_types; t; t = t->next) {
		if (strcmp(type->name, t->name) == 0) {
			/* already found */
			pr_info("Trace %s already registered\n",
				type->name);
			ret = -1;
			goto out;
		}
	}

490
491
492
493
494
495
496
	if (!type->set_flag)
		type->set_flag = &dummy_set_flag;
	if (!type->flags)
		type->flags = &dummy_tracer_flags;
	else
		if (!type->flags->opts)
			type->flags->opts = dummy_tracer_opt;
497
498
499
	if (!type->wait_pipe)
		type->wait_pipe = default_wait_pipe;

500

Steven Rostedt's avatar
Steven Rostedt committed
501
#ifdef CONFIG_FTRACE_STARTUP_TEST
502
	if (type->selftest && !tracing_selftest_disabled) {
Steven Rostedt's avatar
Steven Rostedt committed
503
504
505
		struct tracer *saved_tracer = current_trace;
		struct trace_array *tr = &global_trace;
		int i;
506

Steven Rostedt's avatar
Steven Rostedt committed
507
508
509
510
511
512
513
		/*
		 * Run a selftest on this tracer.
		 * Here we reset the trace buffer, and set the current
		 * tracer to be this tracer. The tracer can then run some
		 * internal tracing to verify that everything is in order.
		 * If we fail, we do not register this tracer.
		 */
Ingo Molnar's avatar
Ingo Molnar committed
514
		for_each_tracing_cpu(i)
515
			tracing_reset(tr, i);
Ingo Molnar's avatar
Ingo Molnar committed
516

Steven Rostedt's avatar
Steven Rostedt committed
517
518
519
520
521
522
523
524
525
526
		current_trace = type;
		/* the test is responsible for initializing and enabling */
		pr_info("Testing tracer %s: ", type->name);
		ret = type->selftest(type, tr);
		/* the test is responsible for resetting too */
		current_trace = saved_tracer;
		if (ret) {
			printk(KERN_CONT "FAILED!\n");
			goto out;
		}
Steven Rostedt's avatar
Steven Rostedt committed
527
		/* Only reset on passing, to avoid touching corrupted buffers */
Ingo Molnar's avatar
Ingo Molnar committed
528
		for_each_tracing_cpu(i)
529
			tracing_reset(tr, i);
Ingo Molnar's avatar
Ingo Molnar committed
530

Steven Rostedt's avatar
Steven Rostedt committed
531
532
533
534
		printk(KERN_CONT "PASSED\n");
	}
#endif

535
536
537
538
539
	type->next = trace_types;
	trace_types = type;
	len = strlen(type->name);
	if (len > max_tracer_type_len)
		max_tracer_type_len = len;
Steven Rostedt's avatar
Steven Rostedt committed
540

541
 out:
542
	tracing_selftest_running = false;
543
544
	mutex_unlock(&trace_types_lock);

Steven Rostedt's avatar
Steven Rostedt committed
545
546
547
548
549
550
551
552
553
554
555
556
	if (ret || !default_bootup_tracer)
		goto out_unlock;

	if (strncmp(default_bootup_tracer, type->name, BOOTUP_TRACER_SIZE))
		goto out_unlock;

	printk(KERN_INFO "Starting tracer '%s'\n", type->name);
	/* Do we want this tracer to start on bootup? */
	tracing_set_tracer(type->name);
	default_bootup_tracer = NULL;
	/* disable other selftests, since this will break it. */
	tracing_selftest_disabled = 1;
557
#ifdef CONFIG_FTRACE_STARTUP_TEST
Steven Rostedt's avatar
Steven Rostedt committed
558
559
	printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
	       type->name);
560
561
#endif

Steven Rostedt's avatar
Steven Rostedt committed
562
 out_unlock:
563
	lock_kernel();
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
	return ret;
}

void unregister_tracer(struct tracer *type)
{
	struct tracer **t;
	int len;

	mutex_lock(&trace_types_lock);
	for (t = &trace_types; *t; t = &(*t)->next) {
		if (*t == type)
			goto found;
	}
	pr_info("Trace %s not registered\n", type->name);
	goto out;

 found:
	*t = (*t)->next;
582
583
584
585
586
587
588
589
590

	if (type == current_trace && tracer_enabled) {
		tracer_enabled = 0;
		tracing_stop();
		if (current_trace->stop)
			current_trace->stop(&global_trace);
		current_trace = &nop_trace;
	}

591
592
593
594
595
596
597
598
599
600
601
602
603
	if (strlen(type->name) != max_tracer_type_len)
		goto out;

	max_tracer_type_len = 0;
	for (t = &trace_types; *t; t = &(*t)->next) {
		len = strlen((*t)->name);
		if (len > max_tracer_type_len)
			max_tracer_type_len = len;
	}
 out:
	mutex_unlock(&trace_types_lock);
}

604
void tracing_reset(struct trace_array *tr, int cpu)
605
{
606
	ftrace_disable_cpu();
607
	ring_buffer_reset_cpu(tr->buffer, cpu);
608
	ftrace_enable_cpu();
609
610
}

611
612
613
614
615
616
617
618
619
620
void tracing_reset_online_cpus(struct trace_array *tr)
{
	int cpu;

	tr->time_start = ftrace_now(tr->cpu);

	for_each_online_cpu(cpu)
		tracing_reset(tr, cpu);
}

621
622
623
624
625
#define SAVED_CMDLINES 128
static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
static int cmdline_idx;
626
static raw_spinlock_t trace_cmdline_lock = __RAW_SPIN_LOCK_UNLOCKED;
627
628

/* temporary disable recording */
629
static atomic_t trace_record_cmdline_disabled __read_mostly;
630
631
632
633
634
635
636
637

static void trace_init_cmdlines(void)
{
	memset(&map_pid_to_cmdline, -1, sizeof(map_pid_to_cmdline));
	memset(&map_cmdline_to_pid, -1, sizeof(map_cmdline_to_pid));
	cmdline_idx = 0;
}

638
639
640
static int trace_stop_count;
static DEFINE_SPINLOCK(tracing_start_lock);

641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
/**
 * ftrace_off_permanent - disable all ftrace code permanently
 *
 * This should only be called when a serious anomally has
 * been detected.  This will turn off the function tracing,
 * ring buffers, and other tracing utilites. It takes no
 * locks and can be called from any context.
 */
void ftrace_off_permanent(void)
{
	tracing_disabled = 1;
	ftrace_stop();
	tracing_off_permanent();
}

656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
/**
 * tracing_start - quick start of the tracer
 *
 * If tracing is enabled but was stopped by tracing_stop,
 * this will start the tracer back up.
 */
void tracing_start(void)
{
	struct ring_buffer *buffer;
	unsigned long flags;

	if (tracing_disabled)
		return;

	spin_lock_irqsave(&tracing_start_lock, flags);
671
672
673
674
675
676
	if (--trace_stop_count) {
		if (trace_stop_count < 0) {
			/* Someone screwed up their debugging */
			WARN_ON_ONCE(1);
			trace_stop_count = 0;
		}
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
		goto out;
	}


	buffer = global_trace.buffer;
	if (buffer)
		ring_buffer_record_enable(buffer);

	buffer = max_tr.buffer;
	if (buffer)
		ring_buffer_record_enable(buffer);

	ftrace_start();
 out:
	spin_unlock_irqrestore(&tracing_start_lock, flags);
}

/**
 * tracing_stop - quick stop of the tracer
 *
 * Light weight way to stop tracing. Use in conjunction with
 * tracing_start.
 */
void tracing_stop(void)
{
	struct ring_buffer *buffer;
	unsigned long flags;

	ftrace_stop();
	spin_lock_irqsave(&tracing_start_lock, flags);
	if (trace_stop_count++)
		goto out;

	buffer = global_trace.buffer;
	if (buffer)
		ring_buffer_record_disable(buffer);

	buffer = max_tr.buffer;
	if (buffer)
		ring_buffer_record_disable(buffer);

 out:
	spin_unlock_irqrestore(&tracing_start_lock, flags);
}

Ingo Molnar's avatar
Ingo Molnar committed
722
void trace_stop_cmdline_recording(void);
723

Ingo Molnar's avatar
Ingo Molnar committed
724
static void trace_save_cmdline(struct task_struct *tsk)
725
726
727
728
729
730
731
732
733
734
735
736
737
{
	unsigned map;
	unsigned idx;

	if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
		return;

	/*
	 * It's not the end of the world if we don't get
	 * the lock, but we also don't want to spin
	 * nor do we want to disable interrupts,
	 * so if we miss here, then better luck next time.
	 */
738
	if (!__raw_spin_trylock(&trace_cmdline_lock))
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
		return;

	idx = map_pid_to_cmdline[tsk->pid];
	if (idx >= SAVED_CMDLINES) {
		idx = (cmdline_idx + 1) % SAVED_CMDLINES;

		map = map_cmdline_to_pid[idx];
		if (map <= PID_MAX_DEFAULT)
			map_pid_to_cmdline[map] = (unsigned)-1;

		map_pid_to_cmdline[tsk->pid] = idx;

		cmdline_idx = idx;
	}

	memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);

756
	__raw_spin_unlock(&trace_cmdline_lock);
757
758
}

759
char *trace_find_cmdline(int pid)
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
{
	char *cmdline = "<...>";
	unsigned map;

	if (!pid)
		return "<idle>";

	if (pid > PID_MAX_DEFAULT)
		goto out;

	map = map_pid_to_cmdline[pid];
	if (map >= SAVED_CMDLINES)
		goto out;

	cmdline = saved_cmdlines[map];

 out:
	return cmdline;
}

Ingo Molnar's avatar
Ingo Molnar committed
780
void tracing_record_cmdline(struct task_struct *tsk)
781
782
783
784
785
786
787
{
	if (atomic_read(&trace_record_cmdline_disabled))
		return;

	trace_save_cmdline(tsk);
}

788
void
789
790
tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
			     int pc)
791
792
793
{
	struct task_struct *tsk = current;

794
795
	entry->preempt_count		= pc & 0xff;
	entry->pid			= (tsk) ? tsk->pid : 0;
796
	entry->tgid               	= (tsk) ? tsk->tgid : 0;
797
	entry->flags =
798
#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
799
		(irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
800
801
802
#else
		TRACE_FLAG_IRQS_NOSUPPORT |
#endif
803
804
805
806
807
		((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
		((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
		(need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
}

808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
struct ring_buffer_event *trace_buffer_lock_reserve(struct trace_array *tr,
						    unsigned char type,
						    unsigned long len,
						    unsigned long flags, int pc)
{
	struct ring_buffer_event *event;

	event = ring_buffer_lock_reserve(tr->buffer, len);
	if (event != NULL) {
		struct trace_entry *ent = ring_buffer_event_data(event);

		tracing_generic_entry_update(ent, flags, pc);
		ent->type = type;
	}

	return event;
}
static void ftrace_trace_stack(struct trace_array *tr,
			       unsigned long flags, int skip, int pc);
static void ftrace_trace_userstack(struct trace_array *tr,
				   unsigned long flags, int pc);

void trace_buffer_unlock_commit(struct trace_array *tr,
				struct ring_buffer_event *event,
				unsigned long flags, int pc)
{
	ring_buffer_unlock_commit(tr->buffer, event);

	ftrace_trace_stack(tr, flags, 6, pc);
	ftrace_trace_userstack(tr, flags, pc);
	trace_wake_up();
}

841
842
843
844
845
846
847
848
849
850
851
852
853
854
struct ring_buffer_event *
trace_current_buffer_lock_reserve(unsigned char type, unsigned long len,
				  unsigned long flags, int pc)
{
	return trace_buffer_lock_reserve(&global_trace,
					 type, len, flags, pc);
}

void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
					unsigned long flags, int pc)
{
	return trace_buffer_unlock_commit(&global_trace, event, flags, pc);
}

Ingo Molnar's avatar
Ingo Molnar committed
855
void
856
trace_function(struct trace_array *tr,
857
858
	       unsigned long ip, unsigned long parent_ip, unsigned long flags,
	       int pc)
859
{
860
	struct ring_buffer_event *event;
861
	struct ftrace_entry *entry;
862

863
864
865
866
	/* If we are reading the ring buffer, don't trace */
	if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
		return;

867
868
	event = trace_buffer_lock_reserve(tr, TRACE_FN, sizeof(*entry),
					  flags, pc);
869
870
871
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
872
873
	entry->ip			= ip;
	entry->parent_ip		= parent_ip;
874
	ring_buffer_unlock_commit(tr->buffer, event);
875
876
}

877
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
878
879
880
881
882
883
884
885
886
887
888
static void __trace_graph_entry(struct trace_array *tr,
				struct ftrace_graph_ent *trace,
				unsigned long flags,
				int pc)
{
	struct ring_buffer_event *event;
	struct ftrace_graph_ent_entry *entry;

	if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
		return;

889
890
	event = trace_buffer_lock_reserve(&global_trace, TRACE_GRAPH_ENT,
					  sizeof(*entry), flags, pc);
891
892
893
894
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
	entry->graph_ent			= *trace;
895
	ring_buffer_unlock_commit(global_trace.buffer, event);
896
897
898
}

static void __trace_graph_return(struct trace_array *tr,
899
				struct ftrace_graph_ret *trace,
900
901
902
903
				unsigned long flags,
				int pc)
{
	struct ring_buffer_event *event;
904
	struct ftrace_graph_ret_entry *entry;
905
906
907
908

	if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
		return;

909
910
	event = trace_buffer_lock_reserve(&global_trace, TRACE_GRAPH_RET,
					  sizeof(*entry), flags, pc);
911
912
913
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
914
	entry->ret				= *trace;
915
	ring_buffer_unlock_commit(global_trace.buffer, event);
916
917
918
}
#endif

Ingo Molnar's avatar
Ingo Molnar committed
919
void
Ingo Molnar's avatar
Ingo Molnar committed
920
ftrace(struct trace_array *tr, struct trace_array_cpu *data,
921
922
       unsigned long ip, unsigned long parent_ip, unsigned long flags,
       int pc)
Ingo Molnar's avatar
Ingo Molnar committed
923
924
{
	if (likely(!atomic_read(&data->disabled)))
925
		trace_function(tr, ip, parent_ip, flags, pc);
Ingo Molnar's avatar
Ingo Molnar committed
926
927
}

928
929
930
static void __ftrace_trace_stack(struct trace_array *tr,
				 unsigned long flags,
				 int skip, int pc)
Ingo Molnar's avatar
Ingo Molnar committed
931
{
932
#ifdef CONFIG_STACKTRACE
933
	struct ring_buffer_event *event;
934
	struct stack_entry *entry;
Ingo Molnar's avatar
Ingo Molnar committed
935
936
	struct stack_trace trace;

937
938
	event = trace_buffer_lock_reserve(tr, TRACE_STACK,
					  sizeof(*entry), flags, pc);
939
940
941
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
942
	memset(&entry->caller, 0, sizeof(entry->caller));
Ingo Molnar's avatar
Ingo Molnar committed
943
944
945
946

	trace.nr_entries	= 0;
	trace.max_entries	= FTRACE_STACK_ENTRIES;
	trace.skip		= skip;
947
	trace.entries		= entry->caller;
Ingo Molnar's avatar
Ingo Molnar committed
948
949

	save_stack_trace(&trace);
950
	ring_buffer_unlock_commit(tr->buffer, event);
951
#endif
Ingo Molnar's avatar
Ingo Molnar committed
952
953
}

954
955
956
957
958
959
960
static void ftrace_trace_stack(struct trace_array *tr,
			       unsigned long flags,
			       int skip, int pc)
{
	if (!(trace_flags & TRACE_ITER_STACKTRACE))
		return;

961
	__ftrace_trace_stack(tr, flags, skip, pc);
962
963
}

964
965
void __trace_stack(struct trace_array *tr,
		   unsigned long flags,
966
		   int skip, int pc)
967
{
968
	__ftrace_trace_stack(tr, flags, skip, pc);
969
970
}

971
static void ftrace_trace_userstack(struct trace_array *tr,
972
				   unsigned long flags, int pc)
973
{
974
#ifdef CONFIG_STACKTRACE
975
	struct ring_buffer_event *event;
976
977
978
979
980
981
	struct userstack_entry *entry;
	struct stack_trace trace;

	if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
		return;

982
983
	event = trace_buffer_lock_reserve(tr, TRACE_USER_STACK,
					  sizeof(*entry), flags, pc);
984
985
986
987
988
989
990
991
992
993
994
995
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);

	memset(&entry->caller, 0, sizeof(entry->caller));

	trace.nr_entries	= 0;
	trace.max_entries	= FTRACE_STACK_ENTRIES;
	trace.skip		= 0;
	trace.entries		= entry->caller;

	save_stack_trace_user(&trace);
996
	ring_buffer_unlock_commit(tr->buffer, event);
997
#endif
998
999
}

1000
1001
#ifdef UNUSED
static void __trace_userstack(struct trace_array *tr, unsigned long flags)
1002
{
1003
	ftrace_trace_userstack(tr, flags, preempt_count());
1004
}
1005
#endif /* UNUSED */
1006

1007
static void
1008
ftrace_trace_special(void *__tr,
1009
1010
		     unsigned long arg1, unsigned long arg2, unsigned long arg3,
		     int pc)
Ingo Molnar's avatar
Ingo Molnar committed
1011
{
1012
	struct ring_buffer_event *event;
Ingo Molnar's avatar
Ingo Molnar committed
1013
	struct trace_array *tr = __tr;
1014
	struct special_entry *entry;
Ingo Molnar's avatar
Ingo Molnar committed
1015

1016
1017
	event = trace_buffer_lock_reserve(tr, TRACE_SPECIAL,
					  sizeof(*entry), 0, pc);
1018
1019
1020
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
1021
1022
1023
	entry->arg1			= arg1;
	entry->arg2			= arg2;
	entry->arg3			= arg3;
1024
	trace_buffer_unlock_commit(tr, event, 0, pc);
Ingo Molnar's avatar
Ingo Molnar committed
1025
1026
}

1027
1028
1029
1030
void
__trace_special(void *__tr, void *__data,
		unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
1031
	ftrace_trace_special(__tr, arg1, arg2, arg3, preempt_count());
1032
1033
}

Ingo Molnar's avatar
Ingo Molnar committed
1034
void
1035
tracing_sched_switch_trace(struct trace_array *tr,
Ingo Molnar's avatar
Ingo Molnar committed
1036
1037
			   struct task_struct *prev,
			   struct task_struct *next,
1038
			   unsigned long flags, int pc)
1039
{
1040
	struct ring_buffer_event *event;
1041
	struct ctx_switch_entry *entry;
1042

1043
1044
	event = trace_buffer_lock_reserve(tr, TRACE_CTX,
					  sizeof(*entry), flags, pc);
1045
1046
1047
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
1048
1049
1050
1051
1052
1053
1054
	entry->prev_pid			= prev->pid;
	entry->prev_prio		= prev->prio;
	entry->prev_state		= prev->state;
	entry->next_pid			= next->pid;
	entry->next_prio		= next->prio;
	entry->next_state		= next->state;
	entry->next_cpu	= task_cpu(next);
1055
	trace_buffer_unlock_commit(tr, event, flags, pc);
1056
1057
}

1058
1059
void
tracing_sched_wakeup_trace(struct trace_array *tr,
Ingo Molnar's avatar
Ingo Molnar committed
1060
1061
			   struct task_struct *wakee,
			   struct task_struct *curr,
1062
			   unsigned long flags, int pc)
1063
{
1064
	struct ring_buffer_event *event;
1065
	struct ctx_switch_entry *entry;
1066

1067
1068
	event = trace_buffer_lock_reserve(tr, TRACE_WAKE,
					  sizeof(*entry), flags, pc);
1069
1070
1071
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
1072
1073
1074
1075
1076
1077
1078
	entry->prev_pid			= curr->pid;
	entry->prev_prio		= curr->prio;
	entry->prev_state		= curr->state;
	entry->next_pid			= wakee->pid;
	entry->next_prio		= wakee->prio;
	entry->next_state		= wakee->state;
	entry->next_cpu			= task_cpu(wakee);
1079
1080
1081
1082

	ring_buffer_unlock_commit(tr->buffer, event);
	ftrace_trace_stack(tr, flags, 6, pc);
	ftrace_trace_userstack(tr, flags, pc);
1083
1084
}

1085
1086
1087
1088
1089
void
ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
	struct trace_array *tr = &global_trace;
	struct trace_array_cpu *data;
1090
	unsigned long flags;
1091
	int cpu;
1092
	int pc;
1093

1094
	if (tracing_disabled)
1095
1096
		return;

1097
	pc = preempt_count();
1098
	local_irq_save(flags);
1099
1100
1101
	cpu = raw_smp_processor_id();
	data = tr->data[cpu];

1102
	if (likely(atomic_inc_return(&data->disabled) == 1))
1103
		ftrace_trace_special(tr, arg1, arg2, arg3, pc);
1104

1105
1106
	atomic_dec(&data->disabled);
	local_irq_restore(flags);
1107
1108
}

1109
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
1110
int trace_graph_entry(struct ftrace_graph_ent *trace)
1111
1112
1113
1114
1115
1116
1117
1118
{
	struct trace_array *tr = &global_trace;
	struct trace_array_cpu *data;
	unsigned long flags;
	long disabled;
	int cpu;
	int pc;

1119
1120
1121
	if (!ftrace_trace_task(current))
		return 0;

1122
1123
1124
	if (!ftrace_graph_addr(trace->func))
		return 0;

1125
	local_irq_save(flags);
1126
1127
1128
1129
1130
	cpu = raw_smp_processor_id();
	data = tr->data[cpu];
	disabled = atomic_inc_return(&data->disabled);
	if (likely(disabled == 1)) {
		pc = preempt_count();
1131
		__trace_graph_entry(tr, trace, flags, pc);
1132
	}
1133
1134
1135
	/* Only do the atomic if it is not already set */
	if (!test_tsk_trace_graph(current))
		set_tsk_trace_graph(current);
1136
	atomic_dec(&data->disabled);
1137
	local_irq_restore(flags);
1138
1139

	return 1;
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
}

void trace_graph_return(struct ftrace_graph_ret *trace)
{
	struct trace_array *tr = &global_trace;
	struct trace_array_cpu *data;
	unsigned long flags;
	long disabled;
	int cpu;
	int pc;

1151
	local_irq_save(flags);
1152
1153
1154
1155
1156
	cpu = raw_smp_processor_id();
	data = tr->data[cpu];
	disabled = atomic_inc_return(&data->disabled);
	if (likely(disabled == 1)) {
		pc = preempt_count();
1157
		__trace_graph_return(tr, trace, flags, pc);
1158
	}
1159
1160
	if (!trace->depth)
		clear_tsk_trace_graph(current);
1161
	atomic_dec(&data->disabled);
1162
	local_irq_restore(flags);
1163
}
1164
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
1165

1166
1167
enum trace_file_type {
	TRACE_FILE_LAT_FMT	= 1,
1168
	TRACE_FILE_ANNOTATE	= 2,
1169
1170
};

1171
static void trace_iterator_increment(struct trace_iterator *iter)
1172
{
1173
1174
1175
	/* Don't allow ftrace to trace into the ring buffers */
	ftrace_disable_cpu();

1176
	iter->idx++;
1177
1178
1179
1180
	if (iter->buffer_iter[iter->cpu])
		ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);

	ftrace_enable_cpu();
1181
1182
}

Ingo Molnar's avatar
Ingo Molnar committed
1183
static struct trace_entry *
1184
peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts)
1185
{
1186
1187
	struct ring_buffer_event *event;
	struct ring_buffer_iter *buf_iter = iter->buffer_iter[cpu];
1188

1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
	/* Don't allow ftrace to trace into the ring buffers */
	ftrace_disable_cpu();

	if (buf_iter)
		event = ring_buffer_iter_peek(buf_iter, ts);
	else
		event = ring_buffer_peek(iter->tr->buffer, cpu, ts);

	ftrace_enable_cpu();

1199
	return event ? ring_buffer_event_data(event) : NULL;
1200
}
1201

1202
static struct trace_entry *
1203
__find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts)
1204
{
1205
	struct ring_buffer *buffer = iter->tr->buffer;
1206
	struct trace_entry *ent, *next = NULL;
1207
	int cpu_file = iter->cpu_file;